This invention relates to a security device for protecting stored sensitive data.
International Patent Application No. WO84/04614 discloses a data security device which includes a container formed of a brittle material such as prestressed glass and which includes a data processor, a volatile CMOS RAM memory device for storing encryption key data, and a battery forming the power supply for the memory device. The container consists of a housing and a lid. The battery is connected to the memory device by a power supply conductor formed in a winding path configuration on the interior surfaces of the housing and the lid, the parts of the power supply conductor on the housing and lid being connected by pairs of contacts at the joint faces between the housing and the lid. The conductor is formed by an evaporated metal thin film material. The power supply conductor pattern is bifilar and the parts of the conductor are interleaved with additional conductors on the interior surfaces of the housing and lid which are grounded or connected to a voltage source. Thus, if the power supply conductor is interrupted or connected to either of the additional conductors the power supply to the volatile RAM would be altered to the degree that the data in the RAM would be destroyed. The known device has the disadvantage of having a relatively low level of security since the width of the power supply conductor provided on the housing must be maintained sufficiently great to enable the provision of an adequate power supply to the memory device. Such relatively wide conductors are subject to the possibility of penetration. For example, it could be possible to produce a hole of sufficiently small diameter to maintain a conductive path in a relatively wide power supply conductor, yet enable unauthorized access to the memory device via the hole. Furthermore, the thin film technology utilized in the manufacture of the known device results in high device cost.
U.S. Pat. No. 4,593,384 issued June 6, 1986 and assigned to the assignee of the present application discloses a security device for the secure storage of sensitive data including a ceramic housing which is formed of six ceramic plates connected together and which contains electronic circuitry including a resettable shift register memory storing sensitive data. The electronic circuitry is mounted on a ceramic support member which is mounted on the bottom plate prior to assembly of the housing. On each plate is provided a pair of conductive path portions disposed in superposed relationship and having complementary zig-zag configurations. The conductive path portions on the plates are interconnected by conductive epoxy interconnections to form first and second conductive paths. Interruption of either conductive path by an attempt to break into the housing causes a reset signal generator to erase the contents of memory. This security device has the disadvantage of being complex in its construction and hence expensive to manufacture.
European Patent Application No. 0142013 discloses a portable data carrier for receiving, storing and outputting information. Data input-output is effected over contactless transfer elements, for example, inductive transfer elements, or over a plug and socket connection. In one embodiment, a printed circuit board carrying circuitry to be protected is enclosed in a housing having sensing sheets provided on the inner surface thereof, which sheets can detect damage to the housing. The sensing sheets are interconnected by contact pins mounted on the circuit board. However, it is not disclosed how a meandering path configuration could be serially interconnected.
It is therefore an object of the present invention to provide a security device for protecting stored sensitive data which is relatively simple to manufacture and hence is a relatively low-cost device, yet which has a high degree of security against unauthorized access.
Therefore, according to a preferred embodiment of the present invention, there is provided a security device for protecting stored sensitive data, including a closed housing containing a memory means adapted to store sensitive data and including a top part, a base part and a plurality of side parts having respective conductive path segments provided thereon, and interconnection means arranged to electronically interconnect said conductive path segments to form conductive path means, the interruption of which, brought about by an attempt to penetrate said housing, causes the erasure of the contents of said memory means, wherein said device includes a printed circuit board on which said memory means is supported, wherein said side plates are mounted on said printed circuit board which is mounted on said base plate, and wherein said interconnection means includes conductive track means provided on said printed circuit board and conductive wires extending from said top part through apertures in said printed circuit board to thereby connect with said conductive track means on said printed circuit board.
It will be appreciated that a security device according to the present invention has the advantage of a simple construction and ease of manufacture. Furthermore since the conductive wires pass through apertures in the printed circuit board, and the side parts are mounted on the printed circuit board, the security module is adapted for simple and secure manufacture.
A preferred embodiment of the present invention will now be described in conjunction with the following description, claims and drawings.